Comparative study on metal ions adsorption on a low cost carbonaceous adsorbent kinetic equilibrium and mechanistic studies
Wastewater generally contains toxic inorganic and organic pollutants. Inorganic pollutants consist of mineral acids, inorganic salts, finely divided metal compounds, trace elements, cyanides, nutrients and organometallic compounds. Some of the trace elements play essential roles in biological processes, but at higher concentrations, they may be toxic to the biota; they disturb the biochemical processes and cause hazards. Heavy metals contamination exists in aqueous waste streams from many industries such as nickel plating, mining, tanneries, and painting, car radiator manufacturing, as well as agricultural sources where fertilizer and fungicidal spray are intensively used. Cu, Fe, Co, Ni, Zn, Cr, Cd, etc., are harmful wastes produced by industries that pose a risk of contaminating groundwater and other water resources. Heavy metals are not biodegradable and tend to accumulate in living organisms, causing various diseases and disorders. For example, chromium causes serious ailments. The treatment process, for removing heavy metals such as iron, cobalt and nickel comprises of chemical precipitation, coagulation, complexation, solvent extraction, ion-change, sorption, osmosis and electrolysis. Adsorption using plant wastes offers an alternative to the other methods as the treatment is single step and no sludge is produced (Chuah et al., 2005).